

Who knows what the problem really was, but I can see and deploy to my device again. I've tried adding the device ID found w/ lsusb to the /.android/adbusb. And, finally, restarting the device normally. In Android Studio, the list of devices and emulators doesn't list my physical device when I plug it in (Google Pixel 2).Enabling USB debugging for development.Restarting the device in Safe-Mode (hold Home + Hangup buttons while powering on), Go to Settings > Developer options, enable: USB debugging Debug mode when USB is connected.Performing a factory data reset on the device (Settings > Privacy > Reset),.I tried the above suggestions, but the device didn't reappear until after: The only change from yesterday that I recall was logging out of my Mac account (as I typically do at the end of the day) and unplugging the USB cable (which I rarely do not). My development device (LG GT540 running Android 2.1, OS X 10.6.8) also mysteriously stopped appearing in "adb devices" today. This issue comes to me after I relocate Android Studio with all folders like.

Just thought I'd mention it because it had us stumped for a bit. If you are running your code from Android Studio, it compiles the code and install the APK on device as regular app (with debugging enabled). Had the same issues with colleagues and found that somehow, "USB Debugging" was disabled in the settings, even though it had worked fine just a few days before. On recent macbook pros, one port will not work consistently.
